A railcar includes a car bodyshell configured by joining an underframe, side bodyshells, end bodyshells, and a roof bodyshell to one another. Typically, the underframe includes: a pair of side sills extending in a car longitudinal direction (rail direction); and a plurality of cross beams coupling the pair of side sills to each other in a car width direction (sleeper direction). Underfloor devices such as a traction transformer are hung by the cross beams through hanging metal fittings.
Especially in a high-speed car, an underfloor portion of the car is covered with an underfloor cover in some cases. The underfloor cover is provided at a lower portion of the underframe along a side of the car for the purpose of: protecting underfloor devices from obstacles, ice and snow accretions, and the like, the underfloor devices being attached to the underfloor portion of the car; regulating the flow of air around the car; and shaping an appearance of the car. PTL 1 describes the underfloor cover (floor pan) for the high-speed car. This underfloor cover is constituted by: a protective floor supported by an underframe through a frame; and side panels each covering a space between a car width direction end of the protective floor and the underframe.
Regarding the underframe of the railcar, a fireproof standard is set in consideration of underfloor fire. For example, in the United States, fire test specimens and fire test methods are defined in ASTM E-119 Standard Methods of Fire Tests of Building Construction and Materials. This provides relative scales regarding the fire tests. One example of the scales is that the temperature of the fire test specimen that is being heated is lower than a specified temperature for a specified period of time.
PTL 2 describes the underframe of the railcar including the fireproof structure. The cross beams of the underframe are covered with a heat insulating material, and this heat insulating material is covered with a heat protection plate. Further, an entire lower surface of an airtight floor supported by the cross beams is covered with a heat insulating material and a heat protection material.